Air Conditioner

ABSTRACT

In a drain water discharging method for force-feeding drain water via a drain pump, clogging of a drain piping is prevented by controlling the drain pump. An air conditioner has a drain pan for collecting drain water that is dropped from a heat exchanger, a drain pump for discharging the drain water in the drain pan, and a DC motor for driving the drain pump. The DC motor for driving the drain pump is controlled to increase its rotating speed when a rotary torque of the DC motor is increased.

TECHNICAL FIELD

The present invention is related to an air conditioner, especially to an air conditioner that prevents drain piping from being clogged.

BACKGROUND OF THE INVENTION

A drain method of force-feeding drain water with a drain pump is applied to some types of air conditioners that are provided at a high position such as air conditioners that are embedded in a ceiling or suspended from a ceiling. A centrifugal pump is generally used as a drain pump that is used in an air conditioner of this type of drain method. In the centrifugal pump, the displacement is automatically changed by a water level of drain water in a drain water storing portion that is pumped up by the drain pump. A trap may be provided to a drain piping that is arranged outside of the air conditioner to avoid a beam in a ceiling. For example, Patent Document 1 discloses such an air conditioner and a prior art of applied examples.

Patent Document 1: Pamphlet of International Publication No. 2004/053398

DISCLOSURE OF THE INVENTION

However, the drain water discharged by the drain pump contains large and small general foreign object, copper powder that is chip of a copper pipe of the piping, wasted tapes of sealing tapes that are used for a connecting portion of the piping, and waste textile that is generated from fibers such as clothes. These foreign object is discharged with drain water when the flow rate of the drain water in the drain piping is fast, even if there is a portion where foreign object is likely to remain, for example, a trap in the drain piping. However, if the flow rate of the drain water in the drain piping is slow, the foreign object remains in the trap, for example, and this may cause clogging. In the drain piping of a drain water discharging method of a natural flowing type that has been conventionally used for long years, the diameter of the drain piping is large and such clogging has not been caused.

An objective of the present invention is to prevent clogging of a drain piping by controlling a drain pump in a drain water discharging method where drain water is force-fed by the drain pump.

One aspect of the present invention provides an air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger, a drain pump for discharging the drain water in the drain pan, and a DC motor for driving the drain pump. The DC motor for driving the drain pump is controlled to increase its rotating speed when a rotary torque of the DC motor is increased.

According to this configuration, foreign object in the drain water remains in a trap when the flow rate of the drain water is slow. Therefore, if the air conditioner is used for a long time, the amount of foreign object that remains in the trap of the drain piping is increased and the remaining amount of foreign object exceeds a predetermined level. This increases the load of the drain pump. As a result, the rotary torque of the DC motor for driving the drain pump is increased. Therefore, if the relationship between the foreign object remaining state and the rotary torque of the DC motor is previously obtained, the foreign object remaining state can be detected from the rotary torque of the DC motor. When it is detected that the predetermined amount of foreign object remains, the rotating speed of the drain pump is increased and the discharged amount of water is increased. This increases the flow rate of the drain water in the drain piping and foreign object remaining in the trap is flowed away at once. Such control prevents clogging of the drain piping.

It is preferable that in addition to the above control, start-stop control of the drain pump is executed according to a water level of the drain water in a drain water storing portion that is pumped up by the drain pump. According to this configuration, the drain pump is less frequently driven when the water amount discharged from the drain pump is small. This prevents clogging more effectively.

Another aspect of the present invention provides an air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger and a drain pump for discharging the drain water in the drain pan. The drain pump is driven after a predetermined time has elapsed from the starting of the air conditioner. According to this configuration, immediately after the air conditioner is started and when the amount of the drain water in the drain water storing portion is small, the drain pump is not driven. This reduces opportunities of the clogging of the drain piping.

Another aspect of the present invention provides an air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger and a drain pump for discharging the drain water in the drain pan.

The drain pump is driven at a predetermined cycle by a timer while the air conditioner is driven. According to this configuration, the driving cycle of the drain pump is appropriately set such that the drain pump is driven when the water level in the drain water storing portion is high and the drain pump is not driven when the water level in the drain water storing portion is low. Accordingly, the foreign object remaining in the drain piping is flowed away before the clogging is caused.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing an air conditioner according to a first embodiment of the present invention;

FIG. 2 is a diagram for explaining a water level sensor in the air conditioner;

FIG. 3 is a flowchart showing activation control of a drain pump in the air conditioner;

FIG. 4 is a flowchart showing activation control of the drain pump in an air conditioner according to a second embodiment of the present invention; and

FIG. 5 is a flowchart showing activation control of the drain pump in an air conditioner according to a third embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

An air conditioner according to a first embodiment of the present invention will now be explained with reference to FIGS. 1 to 3.

According to the first embodiment, the present invention is applied to an air conditioner that is embedded in a ceiling, which is one type of air conditioners that are arranged in high positions. The air conditioner that is embedded in a ceiling according to the first embodiment is an indoor unit of an air conditioner of a separation type and includes a body 1 that accommodates various devices therein and a panel 2 that is arranged at a lower portion of the body 1. The body 1 is put above a ceiling 3 from an opening portion 3 a formed in the ceiling 3 of an air-conditioned room R to be attached to the ceiling 3. The panel 2 is fitted to the opening portion 3 a of the ceiling 3 and is closely attached to a surface of the ceiling that faces the air-conditioned room R. A suction opening 2 a is formed at a center of the panel 2 so as to draw air from the air-conditioned room. Outlets 2 b are formed at four portions in a peripheral portion that surrounds the suction opening 2 a. Air that is cooled or dehumidified is blown from the outlets 2 b.

The body 1 accommodates an air blower 4 and a heat exchanger 5. The air blower 4 draws air in the air-conditioned room into the body 1 via the suction opening 2 a formed at a center of the panel 2 and blows the drawn air toward its outer peripheral direction. The heat exchanger 5 is arranged so as to surround the outer periphery of the air blower 4. A drain pan 6 is arranged at the lower portion of the heat exchanger 5. The drain pan 6 receives drain water that is generated in the heat exchanger 5 and drops therefrom. A drain water storing portion 7 that stores drain water is formed at a portion of the drain pan 6. A drain pump 10 that pumps up drain water from the drain water storing portion 7 is provided to the drain pan 6. In FIG. 1, the heat exchanger 5 is drawn on a left side and a right side of the air blower 4. However, when the heat exchanger 5 is seen from above, the heat exchanger 5 drawn on the left side and the right side of the air blower 4 is integrally formed.

Similarly, the drain pan 6 is drawn on the left side and the right side of the air blower 4 in FIG. 1. However, when the drain pan 6 is seen from above, the drain pan 6 drawn on the left side and the right side of the air blower 4 is integrally formed.

The drain pump 10 is a generally used centrifugal pump that automatically changes its displacement by the level of drain water in the drain water storing portion 7. As shown in FIG. 2, the drain pump 10 has a body housing 12, a DC motor 13, a suction port 14 and a discharge port 15. The body housing 12 accommodates a rotational fan 11 therein. The DC motor 13 drives the fan. The suction port 14 is formed at the lower portion of the body housing 12 and the discharge port 15 discharges the drain water that is pumped up. The drain pump 10 having such a configuration pumps up the drain water from the suction port 14 by centrifugal force that is generated by the rotation of the rotational fan 11 and discharges the drain water from the discharge port 15. A drain piping 16 that is communicated to the outside is connected to the discharge port 15 of the drain pump 10. The discharge amount of the drain pump 10 increases as the water level in the drain water storing portion 7 is higher, and the discharge amount from the drain pump 10 decreases as the water level in the drain water storing portion 7 is lower.

As shown in FIG. 2, a water level sensor 20 is arranged in the drain water storing portion 7. The water level sensor 20 has a float 21 and a support cylinder 22. The float 21 is lifted or lowered according to the change of the water level of drain water. The support cylinder 22 supports the float 21. A contact first point and a second contact point are provided in the support cylinder 22 of the water level sensor 20. The first contact point is activated when the float 21 is positioned at a lower water level A and the second contact point is activated when the float 21 is positioned at an upper water level B. An activation signal from each contact point is transmitted to a controller 25. The lower water level A is set to a position where when the water level is lowered to the lower water level A or lower than the lower water level A, the discharge amount of the drain pump 10 reduces and the flow rate of the drain water in the drain piping 16 cannot be maintained to be a predetermined value or more. The upper water level B is set to a position where if the drain pump 10 is not activated and maintained to be in a non-activated state, the drain water storing portion 7 becomes full.

The controller 25 controls the whole air conditioner and controls the activation of the drain pump 10 as shown by a flowchart in FIG. 3 according to input information from the water level sensor 20. The activation operation of the air conditioner and the activation operation of the drain pump 10 are explained with reference to FIG. 3.

When the air conditioner is activated for a cooling operation or a dehumidifying operation, air in the air-conditioned room R is drawn into the body 1 via the suction opening 2 a by the air blower 4 and the drawn air is cooled or dehumidified by the heat exchanger 5. At this time, the drain water is generated in the heat exchanger 5. The drain water is received in the drain pan 6 and stored in the drain water storing portion 7. The drain pump 10 is not activated until the water level in the drain water storing portion 7 reaches the upper water level B (step S1). When the water level in the drain water storing portion 7 reaches the upper water level B, the drain pump 10 is activated at a standard rotating speed (step S2).

When the air conditioner is used for a long time, foreign object is likely to remain in the trap of the drain piping 16 (not shown). If a predetermined amount of foreign object remains in the drain piping 16, the rotary torque of the drain pump 10 is increased and the rotary torque of the DC motor 13 is increased. According to the present invention, it is determined whether the rotary torque of the DC motor 13 is a predetermined value or less (step S3) and a determination for the remaining state of foreign object in the drain piping 16 is made according to the determination of step S3. In this case, the rotary torque of the DC motor 13 is measured by an appropriate direct or indirect method. For example, the rotary torque of the DC motor 13 may be indirectly measured by the current value of the DC motor 13. If the rotary torque of the DC motor 13 is a predetermined value or less, the air conditioner is continuously activated. If it is determined that the water level in the drain water storing portion 7 is the lower water level A or lower (step S6), the flow rate of the drain water in the drain piping 16 is reduced to the predetermined value or less and foreign object is likely to remain in the drain piping 16. Therefore, the activation of the drain pump 10 is stopped (step S7).

If it is determined that the rotary torque of the DC motor 13 exceeds the predetermined value (step S3), it should be considered that the rotary torque of the DC motor 13 has been increased due to the remaining foreign object of more than the predetermined amount in the drain piping 16. When the discharge amount of the drain pump 10 is increased to increase the flow rate of the drain water in the drain piping 16, the remaining foreign object is flowed away at once. The drain pump 10 is activated for a predetermined period in a state that the rotating speed of the drain pump 10 is increased to the predetermined value (step S4) and the rotating speed of the drain pump 10 is returned to the standard rotating speed after the predetermined period has elapsed (step S5). Thereafter, if the water level of the drain water storing portion 7 is lowered to the predetermined value or lower (step S6), the activation of the drain pump 10 is stopped as described above (step S7). Thereafter, the control operation is executed by repeating the above procedure. Therefore, if it is determined that the rotary torque of the DC motor 13 is still large at the standard rotating speed after the rotating speed of the drain pump 10 is increased for a predetermined period, a control operation is executed such that the rotating speed of the drain pump 10 is increased again for a predetermined period.

According to the air conditioner of the present embodiment having the above configuration, if foreign object of the predetermined amount or more remains in the drain piping 16, the rotating speed of the drain pump 10 is increased for a predetermined period to flow away the foreign object at once. Therefore, the clogging of the drain piping 16 is prevented. The drain pump 10 is controlled to be started or stopped based on the water level of the drain water in the drain water storing portion 7 that is pumped up by the drain pump 10. Therefore, when the water amount discharged from the drain pump 10 is small, the activation number of times of the drain pump 10 is reduced. This further suppresses the foreign object residue in the drain piping 16.

Second Embodiment

In the second embodiment, the control of the drain pump 10 is different from the first embodiment. In other words, at the starting of the operation of the air conditioner, the water level of the drain water in the drain water storing portion 7 is normally low. Therefore, when the drain pump 10 is activated at the starting of the operation of the air conditioner, the discharge amount of the drain pump 10 is small. The foreign object that remains in the drain pan 6 is drawn by the drain pump 10 with the drain water and flowed to the drain piping 16. As a result, the foreign object is likely to remain in the drain piping 16. This control is thus not preferable. In the second embodiment, the water level sensor 20 of the first embodiment is omitted and the same numerals or symbols are applied to the other parts and the explanation thereof is omitted.

According to the second embodiment, the activation of the drain pump 10 is controlled according to the flowchart shown in FIG. 4. When the operation of the air conditioner is started, the activation control of the drain pump 10 is started. When the activation control of the drain pump 10 is started, a timer is reset (step S11). Then, it is determined whether a predetermined time has elapsed by the timer (step S12). After the predetermined time has elapsed, the drain pump 10 is activated (step S13). Thereafter, the drain pump 10 is controlled by repeating this procedure.

In the air conditioner according to the second embodiment, when the air conditioner is started with a small amount of drain water in the drain water storing portion 7, the drain pump 10 is not activated. Therefore, the drain piping 16 is unlikely to be clogged.

Third Embodiment

In the third embodiment, the control of the drain pump 10 is different from the first embodiment. In other words, in the third embodiment, the drain pump 10 is activated at a predetermined cycle with using a timer to increase the discharge amount of the drain pump 10. In the third embodiment, the water level sensor 20 of the first embodiment is omitted and the same numerals or symbols are applied to the other parts and the explanation thereof is omitted.

According to the third embodiment, the activation control is executed according to the flowchart shown in FIG. 5. When the operation of the air conditioner is started, the activation control of the drain pump 10 is started. When the activation of the drain pump 10 is started, the timer is reset (step S21). Then, it is determined whether a predetermined time T1 has elapsed by the timer (step S22). After the predetermined time T1 has elapsed, the drain pump 10 is activated (step S23). Further, it is determined whether the activation time of the drain pump 10 exceeds a predetermined time T2 by the timer (step S24). When the activation time of the drain pump 10 exceeds the predetermined time T2, the activation of the drain pump 10 is stopped (step S25). Thereafter, the control is executed by repeating this procedure such that the drain pump 10 is activated at a predetermined cycle.

According to the air conditioner of the third embodiment, the activation cycle of the drain pump 10 is appropriately set such that the drain pump 10 is activated when the water level in the drain water storing portion 7 is high, and the drain pump 10 is not activated when the water level in the drain water storing portion 7 is low. By setting the activation cycle of the drain pump 10, the clogging of the drain piping 16 is suppressed.

In each of the above-described embodiments, it is preferable that the parts that contact the drain water such as the drain pan 6, the drain pump 10, and the drain piping 16 be formed by an antibacterial material such as a resin material containing an antibacterial agent or an antibacterial metal material such as a copper pipe. If such a material is used in the present invention, a synergistic effect of an antibacterial effect of the antibacterial agent and an effect that the foreign object remaining in the drain piping 16 is flowed away by increasing the flow rate in the drain pump 10 is obtained. The synergistic effect prevents the clogging of the drain piping 16 more effectively.

INDUSTRIAL APPLICATION

The present invention may be applied to an air conditioner that discharges drain water generated in a heat exchanger via a drain pump. 

1. An air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger, a drain pump for discharging the drain water in the drain pan, and a DC motor for driving the drain pump, the air conditioner being characterized in that the DC motor for driving the drain pump is controlled to increase its rotating speed when a rotary torque of the DC motor is increased.
 2. The air conditioner according to claim 1, being characterized in that in addition to said control, start-stop control of the drain pump is executed according to a water level of the drain water in a drain water storing portion that is pumped up by the drain pump.
 3. An air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger and a drain pump for discharging the drain water in the drain pan, the air conditioner being characterized in that the drain pump is driven after a predetermined time has elapsed from the start of operation of the air conditioner.
 4. An air conditioner comprising a drain pan for collecting drain water that is dropped from a heat exchanger and a drain pump for discharging the drain water in the drain pan, the air conditioner being characterized in that the drain pump is driven at a predetermined cycle by a timer during operation of the air conditioner. 